|Daniel Ray Herrera|
Rosario is a mid-level prospect who throws hard and was selected by Baltimore in the last Rule 5 Draft, but ultimately returned to Milwaukee. He struggled as a starter at Advanced Class A Brevard County, with a 5.83 ERA in 14 starts and two relief appearances, and was sent back down to Class A Wisconsin to pitch in relief, the role he had filled in 2010, and struck out 42 batters in 33 2/3 innings. He turns 22 on Sept. 30.
Herrera is a veteran of 115 Major League appearances with the Reds and Brewers, but did not distinguish himself in a very brief stint with Milwaukee earlier this season. He was much more effective at Triple-A Nashville, with a 1.48 ERA and .203 opponents' batting average in 29 games. He turns 27 next month.
"Rosario has a good arm," general manager Doug Melvin said. "And Herrera has pitched very well [at Nashville]. We had a short look with Herrera, but he was in a tough situation."
The Brewers promoted Herrera to the Majors for road series in Chicago and Boston, and he surrendered six hits and four earned runs in 1 2/3 innings.
Herrera was on Milwaukee's 40-man roster, so he technically was claimed off waivers from the Mets. Rosario was formally traded.
Both Herrera and Rosario were on a list of five Minor Leaguers from which the Mets could select two as compensation in the July 12 deal for Rodriguez, who was 3-0 with a 3.12 ERA and 14 holds in his first 19 games with Milwaukee.